South Korea marked the second anniversary Friday of a deadly attack on a frontline island by North Korea.

The November 23, 2010 shelling of Yeonpyeong island killed two South Korean marines and two civilians.

In a condolence ceremony at the War Memorial in Seoul, Prime Minister Kim Hwang-sik called the attack the worst provocation by North Korea since the end of the Korean War in 1953. He added that it was a clear reminder that the two countries are still at war. The war ended in a cease-fire rather than a peace treaty.

As on last year's anniversary, South Korea's military conducted simulated and field drills on western border islands under various scenarios of North Korean attacks. The Joint Chiefs of Staff said the drills involved Marines, the Navy and the Air Force, but did not include live-fire artillery exercises.